It is not a bug, but a bug due to unique situation. Mike knows about it so surely future builds will have this fixed. You can manually fix it if you want:
in UserUpgradeProcessor/PayPal.php, change:
if ($this->_filtered['business'] != strtolower(XenForo_Application::get('options')->payPalPrimaryAccount))
to:
if (strtolower($this->_filtered['business']) != strtolower(XenForo_Application::get('options')->payPalPrimaryAccount))